Gas separation liquefaction means and processes

ABSTRACT

Single or double column cryogenic gas-separation/liquefaction devices, where refrigeration to the device is supplied by a cryocooler alone or by a combination of a cryocooler and by a Joule-Thompson throttling process, where the gas condensation may occur directly on the cold portion of the cryocooler which may be located inside of the thermally insulated space of the distillation column(s) are disclosed. The system is particularly useful for medical applications, such as providing for safe and economical high-purity oxygen for at-home use. The invention principles include a combined column embodiment for simultaneous production of high-purity liquid or gaseous oxygen and nitrogen. Another double column design offers reduced temperature and pressure separation with easy switching between oxygen and nitrogen extraction or single component extraction. If both gaseous and liquid oxygen are required, oxygen purity of approximately 95% can be produced with good recovery, i.e., with nitrogen purity of approximately 91%.

CROSS-REFERENCE TO RELATED APPLICATIONS

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STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR

DEVELOPMENT

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REFERENCE TO SEQUENCE LISTING, A TABLE OR A COMPUTER PROGRAM LISTINGCOMPACT DISK APPENDIX

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BACKGROUND

The present invention relates generally to gas-separation/liquefactionand, more particularly, to a single and double column high-puritycryogenic gas-separation/liquefaction devices, where the refrigerationto the cryogenic gas-separation/liquefaction process is supplied byeither a cryocooler alone or by a combination of a cryocooler and by aJoule-Thompson throttling process, and where the gas condensation mayoccur at least partially directly on the cold portion of the cryocoolerwhich may be located inside of the thermally insulated space of thedistillation column.

The background information discussed below is presented to betterillustrate the novelty and usefulness of the present invention. Thisbackground information is not admitted prior art.

Cryogenic separation of gas mixtures is a well-established art. Theprocesses used to separate the gaseous constituents of ambient air arewell-known and understood. Although all of air's valuable componentssuch as argon, neon, and xenon may be presently extracted from air inhigh-purity concentrations, the mainstay of the separation industry isthe production of nitrogen and oxygen in various purities in gaseous orliquid form, as demanded by the particular application.

The first air separation plant for the commercial production of oxygenwas designed and built by Dr. Carl von Linde in 1902. The plant had asingle distillation column and refrigeration was obtained by throttling.Due to the plant's dependence on ineffective throttling and otherinefficiencies, gaseous oxygen production required pressures of over 30atmospheres, or higher. In the same year, Georges Claude improved on theLinde process by adding an expansion engine to the process. Theexpansion engine, however, proved to be an unreliable component.Therefore, in the late 1930's P. L. Kapitsa proposed and developedexpansion turbines for the separation of oxygen that proved to be farmore reliable than the expansion engine. Moreover, the ability of theexpansion turbines to handle large volumetric flow provided forcryogenic processing at much lower pressures, thus reducing the plantinvestment cost. Since that time, many variations and improvements havebeen made on these devices and their related processes.

A process for the synthesis of methane-oxygen mixtures gas has beendescribed whereby the feeding natural gas and (preferably dry)compressed air into a distillation column at appropriate locations andat appropriate temperatures, produces nitrogen and heavier hydrocarbonsas by-products. In this process, refrigeration is provided by multipleexpansion machines and an expansion valve.

Soon after, a low temperature, single column, distillation process,where the refrigeration is provided by a reciprocating expansion machineand by a throttle valve both external to the distillation column, wasdescribed.

Gas-fractionating devices that provide the reflux for the distillationprocess and that have external refrigeration for condensation where thegas stream that provides the refrigeration and the gas stream to beseparated are distinct, have been discussed, although, the design ofsuch devices was not described.

A process of providing reflux in the distillation column in a refluxcondenser that is refrigerated by a conventional Joule—Thompsonthrottling—work expanding, oxygen rich stream, external to thedistillation column, was also taught.

Cryogenic separation of ethylene from a gaseous mixture at varioustemperature levels using refrigeration provided by an unspecifiedexternal refrigeration system was disclosed.

A process for the recovery of nitrogen from air within a single column,where refrigeration is provided by a turbo-expander, Joule-Thompsonthrottling, has been described.

A device providing for nitrogen rejection from a natural gas stream thatutilizes a series of Joule-Thompson throttle valves to provide thenecessary cooling, instead of external refrigeration, has also beenintroduced into the art. The use of a mixed refrigerant in a single looprefrigeration system providing for at least part of the heat duty of thereboiler is also known.

Most recently, a dephlegmator type separator where the refrigeration isalso supplied by an external supply, was introduced.

It should be noted that even today the irreversible throttling processand the reversible, minus the losses, adiabatic expansion for cryogenicgas-separation/liquefaction, are still practiced almost exclusively.Moreover, it appears that for large tonnage capacity, cryogenicgas-separation/liquefaction plants will be using this technology forsome time to come.

This is not the case, however, in the field of small-scale production ofhigh-purity gases, such as therapeutic oxygen where the immense need forlow-cost, small-scale production of high-purity breathing oxygen iscurrently generating interest in developing small-scale cryogenic-basedgas-separation/liquefaction plants.

Until recently small-scale cryogenic-based gas-separation/liquefactionplants had to rely on periodic cryogenic liquid addition for theirrefrigeration needs. This type of refrigeration, however, is quiteexpensive. Lately, however, reliable cryocoolers of various designscapable of supplying refrigeration at, or below, the liquefactiontemperature of nitrogen have been made available. These cryocoolerscould be eminently suitable for small scale air separation as theyeliminate the need for liquid nitrogen to be delivered to thegas-separation/liquefaction facility.

Applicant is not aware of any device or method wherein at least part ofthe refrigeration required to remove the heat of condensation from thedistillation column reflux is achieved by a cryocooler wherein, innormal operation, a portion of the separated component(s) are condensedat least partially directly on the cold portion of the cryocooler.

SUMMARY

Accordingly, the present invention provides for means and processes thatsatisfy the hereto unmet need for small scale cryogenic air and/or othergas mixture separation where the needed refrigeration is providedwholly, or at least partially, by a cryocooler wherein during normaloperation a portion of the enriched or separated component condenses atleast partially directly onto the cold portion of the cryocooler.

Both single or double column high-purity cryogenicgas-separation/liquefaction devices are embodied within the principlesof the invention where the refrigeration to the cryogenicgas-separation/liquefaction device is supplied by either a cryocooleralone or by a combination of a cryocooler and by a Joule-Thompsonthrottling process, and where the gas condensation may occur at leastpartially directly on the cold portion of the cryocooler which may belocated inside of the thermally insulated space of the distillationcolumn(s).

Using the embodiments described herein, gases, such as high-purityoxygen may be separated from, for example, ambient air in a device ofthe present invention, wherein that device is much smaller thanpresently available gas separation/liquefaction devices. Thus, thesegas-separation/liquefaction systems made according to the principles ofthe present invention are particularly useful for medical applications,and especially for providing for safe and economical high-purity oxygenfor at-home use.

The principles of the invention as taught herein include a combinedcolumn embodiment for the simultaneous production of high-purity liquidor gaseous oxygen and nitrogen. Another double column design offers areduced temperature and pressure separation with an easy switch betweenoxygen and nitrogen extraction or single component extraction. If bothgaseous and liquid oxygen are required, an oxygen purity ofapproximately 95% can be produced with good recovery i.e., with nitrogenpurity of approximately 91%.

These advances in the art and the benefits they provide are accomplishedby providing for a high-purity cryogenic gas-separation/liquefactiondevice for the production of liquid gases that comprises:

a) at least one means for supplying a feed gas;

b) at least one cryogenic means having a cold portion means forproviding refrigeration for at least a process of condensing;

c) at least one condensation means for condensing at least one componentof the feed gas, the condensation means thermally connected to the coldportion means;

d) at least one distillation means for providing for distillation of thecondensed at least one component of the gas, and

e) at least one insulating means for thermally insulating the device,

wherein the refrigeration to the cryogenic gas-separation/liquefactionprocess may be provided by the at least one cryogenic means alone andwhere gas condensation may occur at least partially directly on the coldportion means of the at least one cryogenic means which may be locatedinside of the thermally insulated space of the at least one distillationmeans. It should be understood that in all contemplated applications thecold portion of the cryocooler may be equipped with extended surfacesfor enhanced heat transfer.

It is further contemplated that the high-purity cryogenicgas-separation/liquefaction device further comprises:

a) wherein at least one cryogenic means is a cryocooler,

b) wherein at least one condensation means is a condenser, or the coldportion of the cryocooler.

c) wherein at least one distillation means is a distillation column, and

d) wherein at least one insulating means is a thermally insulatedcontainer,

wherein the refrigeration to the cryogenic gas-separation/liquefactionprocess may be provided by the at least one cryocooler alone and wheregas condensation may occur at least partially directly on the coldportion of the at least one cryocooler which may be located inside oroutside of the thermally insulated space of the at least onedistillation column.

It is still further contemplated that the high-purity cryogenicgas-separation/liquefaction device further comprises:

a) wherein the cryogenic means is a cryocooler,

b) wherein the condensation means is a condenser, or the cold portion ofthe cryocooler.

c) wherein the distillation means is a distillation column, and

d) wherein the insulating means is a Dewar flask,

wherein the refrigeration to the cryogenic gas-separation/liquefactionprocess may be provided by the cryocooler alone and where gascondensation may occur directly on the cold portion of the cryocoolerwhich may be located inside or outside of the Dewar flask of thedistillation column.

Additionally it is contemplated that the high-purity cryogenicgas-separation/liquefaction device also may comprise wherein the feedgas, which may be ambient air or any other gas mixture of interest, maybe driven into the device by a fan or compressor means, and furtherwherein water and carbon dioxide may be removed from the feed gas. Therefrigeration to the cryogenic gas-separation/liquefaction device may beprovided by a combination of the cryogenic means and a Joule-Thompsonthrottling process.

Moreover it is contemplated that the high-purity cryogenicgas-separation/liquefaction device, as recited above may furthercomprise wherein the feed gas passes through a multi-pass heat exchangermeans for cooling and further where the cooled feed gas is introduced tothe at least one distillation means at an appropriate composition point.It is also contemplated that an Interior volume of the at least onedistillation means may be kept at an elevated pressure by a compressor.

Another contemplation comprises using the gas separation/liquefactiondevices of this invention to achieve a high-purity cryogenicgas-separation/liquefaction process for the production of liquid gases,comprising the steps of:

a) supplying a feed gas;

b) providing at least one cryogenic means having a cold portion meansfor providing refrigeration for at least a process of condensing;

c) condensing at least one component of the feed gas using at least onecondensation means thermally connected to the cold portion means; ordirectly on the cold portion means.

d) distilling the at least one component of the condensed gas using atleast one distillation means, and

e) insulating the device using at least one thermally insulating means,

wherein providing the refrigeration to the cryogenicgas-separation/liquefaction process may be by the at least one cryogenicmeans alone and where gas condensation may occur at least partiallydirectly on the cold portion means of the at least one cryogenic meanswhich may be located inside or outside of the thermally insulated spaceof the at least one distillation means.

Furthermore, a high-purity double column cryogenic gasseparation/liquefaction device for the simultaneous collection of aplurality of high-purity liquid gases is contemplated, wherein such adevice comprise:

a) at least one means for supplying a feed gas;

b) a plurality of cryocoolers wherein each cryocooler has a cold portionto provide refrigeration,

c) a plurality of condensing means wherein each condenser means is astandard condenser thermally related to the cold portion of acryocooler, or where the condensing means is a cold finger of thecryocooler.

d) a plurality of distillation columns, and

at least one insulating means for insulating the device,

wherein refrigeration to the cryogenic gas-separation/liquefactionprocess may be provided by the cryocoolers alone and where gascondensation may occur at least partially directly on the cold portionsof the cryocoolers which may be located inside or outside of thethermally insulated space of the distillation column.

Still other benefits and advantages of this invention will becomeapparent to those skilled in the art upon reading and understanding thefollowing detailed specification and related drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

In order that these and other objects, features, and advantages of thepresent invention may be more fully comprehended and appreciated, theinvention will now be described, by way of example, with reference tospecific embodiments thereof which are illustrated in appended drawingswherein like reference characters indicate like parts throughout theseveral figures. The invention will be described and explained withadditional specificity and detail using the accompanying drawings, inwhich:

FIG. 1 is a schematic of a first embodiment of the present invention.

FIG. 2 is a schematic of a second embodiment of the present invention.

FIG. 3 is a plan view of a distillation column functionally situatedinside of a cryogenic Dewar flask.

FIG. 4 is a schematic of another embodiment of a gas separation device,made according to the principles of the invention described herein,where two cryocoolers are used for cooling and condensation.

FIG. 4 a is a schematic of a coil evaporator that may be used as analternative to a conventional condenser.

FIG. 4 b is a schematic of an optional design for a combined coolingsource to reduce total energy consumption.

FIG. 4 c is a schematic of a more effective heat exchange where thecondenser-evaporator is placed at the bottom section of column B.

FIG. 4 d is a schematic of an alternative heat bridge that may be usedin place of condenser 48.

FIG. 4 e is a schematic of the optional use of direct blow-through flow,in which case the condenser could be eliminated.

FIG. 5 is a schematic, in plan view, of double column design for thesimultaneous production of high-purity oxygen and nitrogen according tothe principle of the present invention.

FIG. 6 is a schematic, in plan view, of a variation in design of adouble column gas separator device according to the present invention.

FIG. 7 is a schematic, in plan view, of another variation in design of adouble column gas separator device according to the present invention.

REFERENCE NUMERALS AND THE PARTS OF THE INVENTION TO WHICH THEY REFER

-   1 Conduit through which air may be driven into a gas separation    device of this invention by a fan or compressor means located in an    operative position.-   2 Multi-pass heat exchanger having a warm end (the top part of    exchanger, as illustrated) and a cold end (the bottom part of the    exchanger, as illustrated).-   3 Distillation column.-   4 Insulation about distillation column 3.-   5 Cryocooler (see FIGS. 1, 5, and 7).-   6 Condensing means as exemplified is the cold finger of cryocooler    5.-   7 Expansion value providing for Joule-Thompson expansion.-   8 Conduit for nitrogen-rich stream.-   9 Compressor keeping interior volume 12 of distillation column 3 at    appropriate pressure.-   10 Heat exchanger for removing heat of compression.-   11 Boiler.-   12 Elevated pressure volume of distillation column 3.-   13 Exit point of the gaseous product.-   14 Exit point of liquid product.-   20 Phase separator.-   22 Indicates, in FIG. 2, where air is driven into a gas separation    device of this invention (equivalent to 9).-   23 Heat exchanger for the removal of the heat of compression.-   24 Humidity removal device.-   25 Dew point reduction and removal of carbon dioxide device.-   26 Multi-pass heat exchanger having a warm end (the top part of    exchanger, as illustrated) and a cold end (the bottom part of the    exchanger, as illustrated).-   26 a Exit pathway of gaseous nitrogen enriched stream.-   26 b Exit pathway of the gaseous oxygen from vapor space above    reboiler 28.-   26 c Exit pathway of liquid oxygen that passed through valve V2 on    its way from the liquid pool of reboiler 28.-   27 Compressed air conduit through which gas passes to reboiler (same    function as seen in FIGS. 2, 3, and 5).-   27 a Point where gas stream is separated into two parts.-   27 b Conduit through which one part of stream is fed to heat    exchanger 26 a.-   27 c Conduit through which one part of stream is fed to boiler 50.-   27 d Point where the separated gas streams are rejoined.-   28 Reboiler to vaporize liquid oxygen for operating distillation    column 30.-   29 Expansion value providing for Joule-Thompson expansion (same    function in FIGS. 2 and 3).-   30 Distillation column.-   32 Tube located inside distillation column 30.-   33 Annular fitting bonded to both tube 32 and to conduit 27.-   34 Filter through which compressed air enters the lower section of    the tube 32.-   35 Upper annular fitting.-   36 Center tube.-   37 Liquid distributor.-   38 Spiral guide of packing section.-   40 Indicates, in FIG. 4, compressor to drive air into a gas    separation device of this invention.-   41 Dew point reduction and removal of carbon dioxide device.-   42 Multi-pass heat exchanger having a warm end (the bottom part of    exchanger, as illustrated in FIG. 4) and a cold end (the top part of    the exchanger, as illustrated in FIG. 4).-   43 Boiler for vaporizing liquid oxygen.-   44 Condensing means as exemplified is the cold finger of cryocooler    45.-   44 a Condensing means as exemplified is the cold finger of    cryocooler 45 a.-   45 First cryocooler.-   45 a Second cryocooler.-   46 Collector section of column A.-   47 Filter for liquid air.-   48 Condenser/evaporator.-   48 a Detail of condenser/evaporator.-   49 Conduit for enriched oxygen.-   49A Conduit for enriched nitrogen.-   50 Boiler of distillation column A.-   51 Boiler of distillation column B.-   52 Conduit through which liquid from boiler 51 travels.-   53 Conduit through which non-condensed vapor travels.-   54 Collectors of column B.-   55 Collectors from which high-purity liquid nitrogen may be removed.-   56 Conduit through which highly enriched nitrogen vapor travels.-   60 Condenser.-   61 Liquid conduit.-   62 Collector.-   70 Liquid pump.-   71 First conduit line providing flow connection between column A and    column B.-   72 Second conduit line providing flow connection between column A    and column B.-   A First column.-   B Second column.-   BR Heat bridge.-   V1 Valve to periodically drain CO₂ impurities.-   V2 Valve for collection of oxygen gas containing most of the argon    gas component of feed air.-   V3 Valve for collection of nitrogen liquid.-   V4 Valve.-   V5 Throttling valve.-   V6 Valve shown in FIG. 5 through which enriched liquid oxygen flows    from collectors 54 of column B to enter the top of column A.-   V7 Throttling valve.-   S Coil evaporator used in place of condenser/evaporator 48.-   Cross-hatching denotes separation devices, such as trays, packing,    etc.

Definitions

-   Cold finger, as used herein, refers to a finger-shaped cooled and    cooling protruding member. Where the cryocooler has adequate cooling    capacity, condensation can be carried out on the cold portion of the    cryocooler itself, without employing a separate condenser.-   Condensation, as used herein, refers to the conversion of a    substance from its vapor or gaseous state to its liquid or solid    state usually initiated by a reduction in temperature of the vapor.-   Condenser, as used herein, refers to that part of a distillation    apparatus that cools vapor until it becomes a liquid. There are    several types of condensers. One is simply an inner tube that is    cooled by an outer jacket filled with a liquid like water, for    example. The other type has the inner tube filled with small    (usually glass) beads or other shaped small bits of material. The    distillate is taken from the top. This type of condenser in effect    does thousands of tiny condensations (they occur on each bead) and    produces a much more pure product. To achieve a similar effect with    the other type, you need to do multiple distillations. Where the    cryocooler has adequate cooling capacity, condensation can be    carried out on the cold portion of the cryocooler itself, without    employing a separate condenser.-   Cryocooler, as used herein, refers to any device that can produce    cryogenic temperatures with significant capacity for useful    application. The term cryocooler may denote any of the following:    Gifford-McMahon cryocoolers and any related variations, Stirling    cryocoolers of the crank or linear motor driven variety, the many    variations of the Pulse Tube cryocoolers and combinations of these    with the Stirling refrigerators, reverse Brayton Cycle cryocoolers,    Multi component Vapor Compression cryocoolers, and the like.

Note that providing reflux in the distillation column by condensing aportion of the at least partially separated gas(s) on the cold part ofthe cryocooler would be a common characteristic for any cryocooler.

-   Cryogenics, as used herein, refers to the science concerned with    low-temperature phenomena. Temperatures less than −40 degrees    Celsius are usually classified as cryogenic.-   Dephlegmator, as used herein, refers to a part of a distilling    apparatus in which the separation of the vapors (gases) is effected.-   Dewar or Dewar flask, as used herein, refers to a glass or metal    container made like a vacuum bottle that is used especially for    storing liquefied gases.-   Distillation, as used herein, refers to the process of purifying, or    separating the components of, a mixture by successive evaporation    and condensation.-   Joule-Thompson expansion, as used herein, refers to the cooling that    gas undergoes as it expands.

It should be understood that the drawings are not necessarily to scale.In certain instances, details which are not necessary for anunderstanding of the present invention or which render other detailsdifficult to perceive may have been omitted.

DETAILED DESCRIPTION

Referring now, with more particularity, to the drawings, it should benoted that the disclosed invention is disposed to embodiments in varioussizes, shapes, and forms. Therefore, the embodiments described hereinare provided with the understanding that the present disclosure isintended as illustrative and is not intended to limit the invention tothe embodiments described herein. FIG. 1 schematically illustrates onedevice design and a related process of the present invention.

In the schematic shown in FIG. 1, ambient air, or any other gas mixtureof interest, from which water and carbon dioxide have been removed, isdriven into conduit 1, by a fan or compressor operatively locatedproximal to the entrance of conduit 1. Conduit 1 connects to the warmend of multi-pass heat exchanger 2 (which warm end is located at the topof heat exchanger 2, as illustrated). Low temperature air exits from thecold end of multi-pass heat exchanger 2 (which cold end is located atthe bottom portion of heat exchanger 2, as illustrated) and isintroduced to distillation column 3 at the appropriate compositionpoint.

Distillation column 3 is insulated by insulator 4. Cryocooler 5 isoperatively installed about the top of distillation column 3, as shown.The cold portion of cryocooler 5 is thermally connected to cold finger6. In the embodiment illustrated, the temperature of cold finger 6 isbetween about 77 K and about 88 K (roughly between the boiling point ofliquid nitrogen, about 77 K, and the boiling point of liquid oxygen,about 90 K), or for other gases of interest, between the boiling pointsof the low and high boiling components of the other gas mixtures. Thethermal design geometry and the insulation at the insertion ofcryocooler 5 into column 3 should be carefully optimized to minimizeheat input from the ambient.

Interior volume 12 of distillation column 3 is kept at an elevatedpressure by compressor 9 which is fed a nitrogen-enriched stream as itsworking fluid. The path of travel of the nitrogen-enriched stream isindicated by reference numeral 8. The heat of compression is removedfrom stream 8 by heat exchanger 10 before stream 8 enters the warm endof heat exchanger 2 where it is cooled to an intermediate temperaturebetween the warm and cold end of the exchanger, as required by balancing(not shown). Stream 8 then enters boiler 11 to produce the oxygen-richvapor that is used to operate distillation column 3. Exiting boiler 11,stream 8 is introduced into volume 12 of distillation column 3 wherestream 8 condenses at least partially on cold finger surface 6 ofcryocooler 5. The condensate then undergoes a Joule-Thompson expansionin valve 7 and the liquid reflux is distributed to the top of thedistillation column. The nitrogen-enriched stream exits distillationcolumn 3 from the space between the low-pressure end of theJoule-Thompson expansion valve 7 and the top of the packing or trays ofthe distillation column (denoted by hatching) via conduit 8 and entersthe cold end of the heat exchanger 2. Heat exchanger 2 acts as acounterflow heat exchanger to cool the incoming feed gas against theoutgoing waste and/or product gas; this heat exchanger may be of theregenerator type. Alternatively, high-pressure vapor space 12 at the topend of the distillation column may be connected to the cold end ofconduit 8, through which the nitrogen-enriched stream passes via anappropriately-sized capillary.

Oxygen-rich, gaseous product leaves the vapor space of reboiler 11,enters the cold end of heat exchanger 2 at an appropriate temperaturepoint, and is discharged at room temperature through exit 13. Liquidoxygen product is discharged from boiler 11 at exit 14 through V2.

Although not shown, it will be readily appreciated by those skilled inthe art, all of the cold conduits and the low temperature points of theheat exchanger 2 are kept well-insulated. The cold parts of heatexchanger 2 also may be positioned inside the Dewar flask that may alsocontain distillation column 3. Conversely, the distillation column maybe located inside of one Dewar while the heat exchanger and the coldconduits are kept in another Dewar.

In works by R. A. Gaggioli et al., K. D. Timmerhaus et al., and A. M.Arkharov et al. one, who is well-versed in the art, will find thefundamental physics and physical chemistry required for constructing oneof the above described novel cryogenic separation systems according tothe principles taught herein and will also find the procedures necessaryfor balancing the system around a given component, such as a cryocooler.

Another contemplated embodiment for the cryogenic separation of airusing a cryocooler is illustrated schematically in FIG. 2. Ambient air,or any other gas mixture of interest, is compressed to a relativelylow-pressure, typically, but not necessarily, less than around 0.8 MPa,by compressor 22. The heat of compression is removed in heat exchanger23 and the condensed humidity is removed in humidity exchanger 24. Thecooled and dried compressed air then enters dew point reduction device25 (suggested types of available dew point reduction devices are givenbelow) to reduce the dew point of the cooled and dried compressed air toa desired low level and to remove CO₂ to prevent plugging in the lowtemperature parts of the system. The humidity and carbon dioxide removalcan be effected by any known, or yet to be known, device, such assemi-permeable membranes, adsorption devices, or by any combination ofthe known methods. After leaving device 25, the compressed, clean airenters the warm end of heat exchanger 26 where it will be cooled downagainst the cold outgoing product and waste gases. The cooled air isthen introduced through conduit 27 to reboiler 28 where liquid oxygen isvaporized and collected in the bottom of the distillation column toenable proper functioning of the same. Partially condensed in thereboiler 28, the compressed air undergoes a Joule-Thompson expansion invalve 29 where the temperature will be reduced further causing theliquid mass fraction to increase. The liquid and gas phases will beseparated in phase separator 20, and introduced into the distillationcolumn 30 at the appropriate composition points. Cold finer 6 ofcryocooler 5 will provide part of the liquid required for the operationof distillation column 30. The gaseous nitrogen enriched stream iswithdrawn from the gas space at the top of the column along pathway 26a, gaseous enriched oxygen is withdrawn from the vapor space abovereboiler 28 along pathway 26 b, and liquid oxygen from the liquid poolof the reboiler, after passing through trough valve V2, is withdrawnthrough pathway 26 c. The separated gases (enriched oxygen and enrichednitrogen) will be warmed up concurrently against incoming air in heatexchanger 26. If both gaseous and liquid oxygen are required, an oxygenpurity of approximately 95% can be produced with good recovery i.e.,with nitrogen purity of approximately 91%.

FIG. 3 illustrates a distillation column functionally positioned insideof insulating cryogenic Dewar flask 4, which flask may be made of metalor glass. Compressed air enters the device via conduit 27 (having thesame function as the conduit 27 in FIG. 2) at the top of the flask,which conduit is in close proximity to the length of distillation column30. The compressed air travels down conduit 27 forming a spiral in theliquid pool affecting reboiler 28. Distillation column 30 is constructedin an annular fashion with tube 32 located inside distillation column30. As illustrated in FIG. 3, the packing (denoted by hatching) isdivided into two portions. Compressed air from conduit 27 enters tube 32near the bottom of the distillation column. Annular fitting 33 is bondedto both tube 32 and to conduit 27 so that compressed air enters thelower section of the tube 32 first through filter 34, which is optional,then through upper annular fitting 35 to finally enter into center tube36. Tube 36 ends in capillary fitting 29 (same function as mentioned indiscussion relating to FIG. 2) and will discharge a mixture of gaseousvapor and liquid into elevated pressure volume 12 of the distillationcolumn. The liquid phase will join the condensate obtained on coldfinger 6 of cryocooler 5 and will be distributed through sieve 37 toprovide the reflux. The gaseous phase will be returned downward in theannulus formed by tube 32 and the center tube 36 to an appropriateconcentration location of the distillation column packing or trays.Drillings or slots provided in tube 32 (not shown) will let this gasportion join the gas phase of the distillation column at the appropriateconcentration height.

Compactness of the unit is achieved by the optional use of spiral guide38 of packing sections in the distillation columns. In such a design thevapor goes upward along a spiral path as the reflux is distributeddownward through each loop by gravity and capillary forces.

Yet another embodiment, as illustrated in FIG. 4, offers a double columndesign for the simultaneous production of high-purity oxygen andnitrogen, where enhanced performance of the system is achieved using twocryocoolers for cooling and condensation. Here, feed air is compressedby 40. Water vapor and carbon dioxide are then removed from thecompressed air in device 41. The cleaned and compressed air then travelsthrough multi-pass heat exchanger 42, which exchanger has a warm end(the bottom part of exchanger, as illustrated in FIG. 4) and a cold end(the top part of the exchanger, as illustrated in FIG. 4) (these partsare similar to parts 22, 25, and 26 of FIG. 2, respectively). The air isthen conveyed to boiler 43 where the liquid oxygen is vaporized in thebottom section of column B. The partially condensed stream is fed tocold finger 44 at the upper section of column A where additionalcondensate will be formed. Cold finger 44 is part of the cold end offirst cryocooler 45. Alternatively, condensation may occur at leastpartially directly on the cold end of cryocooler 45. The condensed airwith the remaining CO₂ impurities will drip down into the collectorsection 46 of column A wherefrom it may be periodically drained throughvalve V1. The liquid air, after passing through filter 47 will beintroduced to the condenser-evaporator 48 (which may be of the commontype, as illustrated in as 48A) of column B where it is partiallyvaporized. The gaseous phase is fed to the appropriate concentrationpoint of the upper section of column B through V4 and separated in agas-liquid contacting device due to rectification with the downstreamliquid. The liquid stream/ vapor balance in column B is maintained bycold finger 44 a which is cold part of second cryocooler 45 a.Alternatively, condensation may occur at least partially directly on thecold end of cryocooler. Separated oxygen gas containing most of theargon gas component of the feed air and nitrogen liquid may leave thecolumn through valves V2 and V3, respectively. Enriched oxygen andnitrogen gas flows through conduits 49 and 49A respectively and will beutilized in heat exchanger 42 to pre-cool the incoming air. This designallows high-purity co-production of oxygen in gaseous and liquid formand of nitrogen.

FIGS. 4 a, 4 b, 4 c, 4 d, and 4 e show alternate designs for selectedstructural parts of the invention as described in connection with FIG.4. FIG. 4 a illustrates coil evaporator S used in place ofcondenser/evaporator 48 (as illustrated in FIG. 4). FIG. 4 b illustratesthe use of a combined cooling source which will reduce the total energyconsumption. More effective heat exchange could be achieved using thealternative design illustrated in FIG. 4 c where thecondenser-evaporator is placed at the bottom section of column B.Condenser 48 (as illustrated in FIG. 4) may be replaced by heat bridgeBR as depicted in FIG. 4 d or completely eliminated from the device ifdirect blow-through flow is utilized per FIG. 4 e. The schemes presentedin 4 d and 4 e may necessitate utilization of a heat bridge 43 a.

FIG. 5 illustrates a double column design for the simultaneousproduction of high-purity oxygen and nitrogen, using any cooling devicewherein the cold portion of the cooling device is installed directlyinto the distillation column. H₂O and CO₂ are first removed fromcompressed air as described above. The cleaned and compressed air thenenters the system through conduit 27 and is then sent through a two partheat exchanger, having sections 26 and 26 a. At point 27 a between heatexchanger sections 26 and 26 a, the air stream is split into twostreams. One stream is fed through conduit 27 c to boiler 50 ofdistillation column A where it is partially condensed. The second streamis fed through conduit 27 b to heat exchanger 26 a where it willexchange heat with the countercurrent flow of enriched nitrogen vaporthat travels through conduit 56 before entering boiler 51 ofdistillation column B. The first and second streams then will berejoined at 27 d and fed into column B at the appropriate concentrationpoint. Liquid from boiler 51, travels through conduit 52 to throttlingvalve V5 entering cold finger 44 at the top of column B (cold finger 44part of the cryocooler cooling device 45 is functionally the same as thecold finger 44 a in FIG. 4). Liquid reflux generated by valve V5 andcold finger 6 will irrigate the packing or the feed trays, asappropriate. The non-condensed vapor in conduit 53 will be fed to theappropriate concentration section of column B. The liquid fromcollectors 54 of column B travels through valve V6 to enter the top ofcolumn A. High-purity liquid oxygen will be removed from the bottom ofcolumn A and high-purity liquid nitrogen may be removed from collectors55. Column A is operated at near atmospheric pressure while column B isat the pressure provided by the compressor.

FIG. 6 shows another combined column embodiment designed for thesimultaneous production of liquid or gaseous oxygen and nitrogen. Afterthe temperature of the compressed and purified feed air is appropriatelyreduced in heat exchanger 26, the air is fed to the mid-section ofdistillation column B by conduit line 27. Distillation columns A and B,in this embodiment are combined into one, two-par, unit where the twoparts are separated by condenser 60, which is functionally positioned onthe bottom section of column A. Condensate from high-pressuredistillation column B passes through liquid line 61 and throttle valveV7 to the mid-section of low-pressure distillation column A. Enrichednitrogen gas is withdrawn from the top of column A trough conduit 8 andexchanges heat in heat exchanger 26 against the incoming compressed,purified air. High-purity liquid oxygen exits at the bottom section ofcolumn A through valve V2 and liquid nitrogen passes through collectors62 to exit through valve V3 located in this example near the top ofcolumn B.

Another double column design is illustrated in FIG. 7. The mainadvantage of this design is that this system provides for a reduction ofboth temperature and pressure process conditions, as well as an easyswitch between the production of both oxygen and nitrogen or singlecomponent extraction. Condenser 60 is operatively placed at the bottomsection of column A. Liquid pump 70 located on conduit line 72 providesthe flow connection between condenser 60 and distillation column B.Products are extracted in the same manner as described above in thediscussion relating to the embodiment illustrated in FIG. 6.

The foregoing description, for purposes of explanation, uses specificand defined nomenclature to provide a thorough understanding of theinvention. However, it will be apparent to one skilled in the art thatthe specific details are not required in order to practice theinvention. Thus, the foregoing description of the specific embodiment ispresented for purposes of illustration and description and is notintended to be exhaustive or to limit the invention to the precise formdisclosed. Those skilled in the art will recognize that many changes maybe made to the features, to the way that some of the parts of the devicemay be arranged relative to one another creating various embodiments, aswell as methods of making the embodiments of the invention describedherein without departing from the spirit and scope of the invention.Thus, it is to be understood that the present invention is not limitedto the described exemplary methods, embodiments, features orcombinations of features but include all the variation, methods,modifications, and combinations of features within the scope of theappended claims. The invention is limited only by the claims.

1. A high-purity cryogenic gas-separation/liquefaction device for theproduction of liquid gases, comprising: a) at least one means forsupplying a feed gas; b) at least one counterflow heat exchanger to coolthe incoming feed gas against the outgoing waste and/or product gas; c)at least one cryogenic means having a cold portion means for providingrefrigeration for at least a process of condensing; d) at least onecondensation means for condensing at least one enriched component of thefeed gas, said condensation means thermally connected to said coldportion means; or directly on the cold portion means. e) at least onedistillation means for providing for distillation of the condensed atleast one component of the gas; f) at least one insulating means forthermally insulating said device, and g) liquid collecting means tocollect and store one or two liquid products, as desired, wherein therefrigeration to the cryogenic gas-separation/liquefaction process maybe provided by said at least one cryogenic means alone and where gascondensation may occur at least partially directly on the cold portionmeans of said at least one cryogenic means which may be located insideof the thermally insulated space of the said at least one distillationmeans.
 2. The high-purity cryogenic gas-separation/liquefaction device,as recited in claim 1, further comprising: a) wherein at least onecryogenic means is a cryocooler, b) wherein at least one condensationmeans is a condenser, or directly on the cold portion of the cryocooler.c) wherein at least one distillation means is a distillation column, andd) wherein at least one insulating means is a thermally insulatedcontainer, wherein the refrigeration to the cryogenicgas-separation/liquefaction process may be provided by said at least onecryocooler alone and where gas condensation may occur directly on thecold portion of said at least one cryocooler which may be located insideor outside of the thermally insulated space of the said at least onedistillation column.
 3. The high-purity cryogenicgas-separation/liquefaction device, as recited in claim 2, furthercomprising: a) wherein said cryogenic means is a cryocooler, b) whereinsaid condensation means is a standard condenser thermally related to thecold portion of a cryocooler, or where the condensing means is a coldfinger of the cryocooler. c) wherein said distillation means is adistillation column, and d) wherein said insulating means is a Dewarflask, wherein the refrigeration to the cryogenicgas-separation/liquefaction process may be provided by said cryocooleralone and where gas condensation may occur directly on the cold portionof said cryocooler which may be located inside or outside of the Dewarflask of said distillation column.
 4. The high-purity cryogenicgas-separation/liquefaction device, as recited in claim 1, furthercomprising wherein refrigeration to the cryogenicgas-separation/liquefaction device may be provided by a combination ofsaid cryogenic means and a Joule-Thompson throttling process.
 5. Thehigh-purity cryogenic gas-separation/liquefaction device, as recited inclaim 1, further comprising wherein said feed gas may comprise ambientair or any other gas mixture of interest.
 6. The high-purity cryogenicgas-separation/liquefaction device, as recited in claim 1, furthercomprising wherein water and carbon dioxide are removed from said feedgas.
 7. The high-purity cryogenic gas-separation/liquefaction device, asrecited in claim 1, further comprising wherein said feed gas is driveninto said device by a fan or compressor means.
 8. The high-puritycryogenic gas-separation/liquefaction device, as recited in claim 1,further comprising wherein said feed gas passes through a multi-passheat exchanger means for cooling.
 9. The high-purity cryogenicgas-separation/liquefaction device, as recited in claim 1, furthercomprising wherein said cooled feed gas is introduced to said at leastone distillation means at an appropriate composition point.
 10. Thehigh-purity cryogenic gas-separation/liquefaction device, as recited inclaim 1, further comprising wherein an Interior volume of said at leastone distillation means is kept at an elevated pressure by a compressor.11. A high-purity cryogenic gas-separation/liquefaction process for theproduction of liquid gases, comprising the steps of: a) supplying a feedgas; b) at least one counterflow heat exchanger to cool the incomingfeed gas against the outgoing waste and/or product gas; c) providing atleast one cryogenic means having a cold portion means for providingrefrigeration for at least a process of condensing; d) condensing atleast one enriched component of the feed gas using at least onecondensation means thermally connected to said cold portion means orcondensing at least one enriched component of the feed gas directly onthe cold portion means. e) distilling said at least one component of thecondensed gas using at least one distillation means; f) insulating saiddevice using at least one thermally insulating means, and g) collectingliquid in liquid collecting means to collect and store one or two liquidproducts, as desired, wherein providing the refrigeration to thecryogenic gas-separation/liquefaction process may be by said at leastone cryogenic means alone and where gas condensation may occur at leastpartially directly on the cold portion means of said at least onecryogenic means which may be located inside or outside of the thermallyinsulated space of the said at least one distillation means.
 12. Thehigh-purity cryogenic gas-separation/liquefaction process, as recited inclaim 11, further comprising wherein providing refrigeration to thecryogenic gas-separation/liquefaction device may be by a combination ofsaid cryogenic means and a Joule-Thompson throttling process.
 13. Thehigh-purity cryogenic gas-separation/liquefaction process, as recited inclaim 11, further comprising wherein said feed gas may comprise ambientair or any other gas mixture of interest.
 14. The high-purity cryogenicgas-separation/liquefaction process, as recited in claim 11, furthercomprising removing water and carbon dioxide from said feed gas.
 15. Thehigh-purity cryogenic gas-separation/liquefaction process, as recited inclaim 11, further comprising driving said feed gas into said device by afan or compressor means.
 16. The high-purity cryogenicgas-separation/liquefaction process, as recited in claim 11, furthercomprising passing said feed gas through a multi-pass heat exchangermeans for cooling.
 17. The high-purity cryogenicgas-separation/liquefaction process, as recited in claim 11, furthercomprising introducing said cooled feed gas to said at least onedistillation means at an appropriate composition point.
 18. Thehigh-purity cryogenic gas-separation/liquefaction process, as recited inclaim 11, further comprising wherein an interior volume of said at leastone distillation means is kept at an elevated pressure by a compressor.19. The high-purity cryogenic gas-separation/liquefaction process, asrecited in claim 11, further comprising utilizing at least one boiler toproduce an enriched vapor to operate said at least one distillationcolumn.
 20. A high-purity double column cryogenicgas-separation/liquefaction device for the simultaneous collection of aplurality of high-purity liquid gases, comprising: a) at least one meansfor supplying a feed gas; b) at least one counterflow heat exchanger tocool the incoming feed gas against the outgoing waste and/or productgas; c) a plurality of cryocoolers wherein each cryocooler has a coldportion to provide refrigeration, d) a plurality of condensers whereineach condenser is thermally related to the cold portion of a cryocooler,e) a plurality of distillation columns; f) at least one insulating meansfor insulating said device, and g) liquid collecting means to collectand store one or two liquid products, as desired, wherein refrigerationto the cryogenic gas-separation/liquefaction process may be provided bysaid cryocoolers alone and where gas condensation may occur at leastpartially directly on the cold portions of the cryocoolers which may belocated inside or outside of the thermally insulated space of thedistillation column.